Terror of the forest

New Zealand’s forests were once the home of the largest eagle in the world. This normous bird had claws as big as a tiger’s, and could strike its prey with the force of a concrete block dropped from the top of an eight-storey building.

The South Island Maori tell the story of Pouakai, a gigan­tic bird of prey which terror­ised the local people. Pouakai (liter­ally ‘old glutton’) would regularly swoop down and carry off men, women and children to its eyrie on Mt Torlesse. None could escape its sharp talons, and the mighty rush of its wings struck fear into the hearts of all who heard it.

One day a visiting warrior, Te Hau o Tawera, heard of the plight of the people and volunteered to get rid of the monster. Taking 50 armed men with him, he crept up to the foot of the mountain in the dead of night and built a large trap out of manuka saplings At first light, while the 50 warriors hid inside the trap, Hautere ventured forth to lure Pouakai from its nest.

The giant bird soon spied Hautere and swooped down to devour him. Sprinting for his life, Hautere just made it back to the trap before the bird pounced on him. At that mo­ment the warriors sprang from their hiding place and speared Pouakai to death.

This story may be one of mankind’s last, faint recollections of the largest eagle which has ever lived. A bird with a wingspan of up to three metres. A bird which could fell an adult moa, weighing from 100 to 250 kilograms, at a single strike.

It is not surprising that such an impressive predator left its mark on the minds of the early inhabitants of these islands. An eagle which spe­cialised in hunting large bipeds may have occasionally mistaken the new arrivals in its territory for its regular prey, especially when the animal was wearing a feather cloak!

Pouakai would have stood in sharp contrast to the rest of New Zealand’s birds, which, having evolved in the absence of mammal­ian predators, would have been naive and unafraid of man.

As it is, most of what we know about this giant eagle has come from its bones, found in swamps and caves. The first discovery of eagle bones was made nearly 120 years ago. It was the summer of 1871, and the Canterbury Museum’s taxider­mist was supervising an excavation of moa bones from a swamp on Mr George Moore’s estate in Glenmark. Dr Julius Haast, the museum’s direc­tor, had arranged the excavation and he published the results, but the hard work of digging five to six feet into the swamp was left to estate workers, and to Frederick Richardson Fuller, the taxidermist. Fuller happened to be on hand when some smaller bones were unearthed among the moa remains, and immediately recog­nised them as belonging to a giant bird of prey.

It is one of the quirks of history that the person who discovered the eagle is now nearly forgotten. When Haast read his description of the bones before the Canterbury Philo­sophical Society in May 1871, he gave Fuller the credit for discovering it, but events then passed the taxi­dermist by. Haast has his immortal­ity in the authorship of the name; Moore, whose generosity to Haast in letting him excavate and keep bones worth thousands of pounds, was rewarded in the eagle’s scientific name — Harpagornis moorei. But Fuller, after his moment of glory, got nothing.

In 1876 Haast suspended him for drinking and reported him to the Museum Board. According to Haast’s son Heinrich, the Board dismissed Fuller and he could not get his case heard. He poisoned himself with arsenic and refused the stomach pump, the jury’s verdict being “poi­soned with arsenic during tempo­rary insanity”. Perhaps the arsenic or mercury-based preservatives used by taxidermists had accumulated in his system over the years and caused his fatal depression.

The eagle bones Fuller found were a femur, a rib, and two claws. This was not much to go on when describ­ing a new species, and Haast rather broke with tradition in describing the bones himself. Important new material was usually sent to England for examination and description by one of the great authorities on anat­omy, such as Sir Richard Owen.

Somewhat apologetically, Haast pointed out that he had described the bird himself, despite the almost complete lack of specimens to com­pare it with, because he did not wish to take the chance of sending such valuable specimens on the long sail­ing voyage to England. This excuse was not unreasonable. Other irre­placeable items had been lost at sea. The ships carrying the only speci­men of a huge New Zealand moth and several fossil reptiles had van­ished without trace.

Haast could be excused for keep­ing such a prize for himself, and he later sent photographs and plaster casts of eagle bones to Owen. Ironi­cally, Owen had had access to a bone of Haast’s eagle for nearly twenty years before the Glenmark find, but didn’t know it. Walter Mantell, a leading Wellington colonist, had collected bones from middens in both islands in the 1840s and sold them to the British Museum. Among the bones was an eagle wing bone, not mentioned in print until 1891. It is still in the museum, along with Haast’s casts.

The summer excavations at Glen-mark continued. Each year the mu­seum bullock wagon rumbled the 60 kilometres back to Christchurch laden with the moa bones which Haast described or sent to Europe and America in exchange for exhib­its for ‘his’ museum. In the 1873 season, Haast’s men found more eagle bones Haast thought some of these were from the same bird he had de­scribed in 1871. Many others, from a smaller bird, were found on the other side of the stream. The cautious Haast noted that they probably came from the male of the first species — male birds of prey are often much smaller than females — but described them as a new species, Harpagornis as­similis. For a naturalist in the An­tipodes, anxious to further his repu­tation among the distinguished names of Europe, naming two spe­cies of huge eagle was better than naming one.

Haast had skeletons of only four birds of prey with which to compare his eagle’s bones. Not unnaturally, he concluded that it was related to these, perhaps most closely to the harrier, but similar in other ways to the falcon. Later, other experts thought it was closer to either the sea eagles or the golden eagle group. Haast’s eagle is now thought to be related to both the forest eagles of Africa and south-east Asia and to the golden eagles, which include the Australian wedge-tailed eagle.

Although related to the golden eagles, which live in open country, it would have looked quite different, because it lived in the forest and shrubland which covered New Zea­land before the coming of man In structure, colour pattern and behav­iour it was probably similar to the great forest eagles such as the Harpy of South America and the Philippine eagle.

The largest eagle in the world today, a female Harpy, weighs up to nine or ten kilograms. A female Haast’s eagle, weighing as much as 13 kilograms, could have struck its prey with the energy of a rifle bullet.

The proportions of its wing bones have convinced some recent work­ers that the eagle was losing the power of flight, but there is good evidence that it was a powerful flier. The ulna, the main forearm bone, is proportionately shorter than in other birds of prey, but the wing as a whole was a normal length for the bird’s size. The different proportions were related to the way it flew. The wing and leg bones have large scars where powerful flight and gripping muscles were anchored. The huge claw bones are as large as those of a tiger.

The habits and anatomy of the eagle were not the only questions confronting Haast and his colleagues. There was the important problem of when Harpagornis, and its prey, had become extinct. It was obvious that eagles and moa had coexisted for many thousands of years, because their bones had been found together under 60 feet of gravel deposited during glacial times. This observa­tion was confirmed in the 1970s when bones found in old estuarine deposits near Oamaru were found to be about 30,000 years old.

But how long had men coexisted with moa, and were eagles still alive when the first canoes made landfall? In the 1870s, 80 years before carbon dating was invented, no one could even say how long people had been in New Zealand.

Evidence that the eagle had lived alongside man was unearthed in Sumner Cave in the 1870s. One of the artefacts from an early level in the cave, a bone awl, was carved from an eagle bone. Unfortunately, Haast misidentified it as from a giant petrel. In the 1940s Dr Roger Duff and Jim Eyles found other eagle bone artefacts at the Wairau Bar moa­hunter site. Although it is possible that the tools were made from old bones, fresh swan and albatross bones were readily available. Why would a toolmaker want to hunt for rare fos­sils? This, and the appearance of the tools themselves, suggests that they were cut from the bones of eagles killed by the toolmakers.

Although he missed the bone awl, Haast just may have seen a living eagle himself. His survey party was sitting around their campfire in the headwaters of the Rakaia one eve­ning when a large bird of prey crashed into their tent. Before anyone could reach for a gun, the bird recovered its senses and flew away. It was larger and darker than the harrier, with more pointed wings, and Haast thought that it could have been Har­pagornis.

Other birds, such as the takahe, have survived in remote places long after they have become extinct in inhabited areas, but it is unlikely that Haast’s living bird was Harpa­gornis. The eagle’s habitat had long gone, its prey had been extinct for several hundred years, and the living bird almost certainly had broad, rounded wings, like those of other forest eagles. Besides, if the eagle had survived into the 19th century the Maori would surely have had stronger recollections of it.

Apart from the Pouakai legend, the only tradition which has been linked with the eagle is one about the Hokioi, a very powerful bird which used to live in the mountains. Gover­nor Grey was told that it was as large as a moa, had black feathers tinged with yellow and green, and had a bunch of red feathers on top of its head. The Hokioi was said to be the harrier’s great rival, and was recog­nised by the noise of its wings during flight.

Dramatic drawings on the walls of South Island rock shelters provide further evidence that early New Zealanders were familiar with eagles. Some of the images show finger-like primary feathers at the tips of broad wings and are almost certainly pic­tures of large eagles. The artist who painted the great bird on the roof of the Craigmore shelter was drawing from his own experience one of the most dramatic animals he knew. The eagle had reigned supreme for mil­lennia in the forests which had once surrounded the shelter, and to men huddled around a campfire it would have been a powerful symbol of the forces of nature.

In a shelter at Weka Pass, near Glenmark, is another image, painted on the rock wall above a campsite used four or five hundred years ago. The bird’s legs are strong and bent, with big talons. In life, Haast’s eagle had the most powerful legs and feet of any bird of prey, living or extinct.

Harpagornis would have been a powerful totem figure for the early inhabitants, perhaps inspiring cere­monies like those of the eagle cults of the western and northwestern United States. But memory of the eagle, like the moa, would have faded quickly after its extinction. The need to make a living in a depleted environment would have overshadowed the old memories when the forests and moa had gone.

People’s minds were more on the products of the sea than the land in these harder times, and the eagle was mainly a South Island bird by the time Polynesians arrived. Human population declined in the south after the supply of moa and seals ran out, and the South Island tribes were replaced by successive waves of northern invaders with their own traditions. Local stories would have faded all the faster.

Until the Polynesians arrived, perhaps a thousand years ago, Haast’s eagle frequented the drier eastern forests which covered the eastern and southern South Island from the mountains to the sea. Here its prey of geese and moa lived in the rich mosaic of forest, scrub, and patches of riverside grassland. It would not have survived in any numbers into the Polynesian times in the damp forests of the West Coast or the North Island.

In the period of burning and moa­hunting which followed colonisa­tion, the habitat and foods of the eagle quickly vanished. The eagle, like the sabre-toothed cats of North America, was adapted for killing large prey. When the habitat changed and the prey (mammoths in North America, moa and other flightless birds in New Zealand) were extermi­nated, the big predators died out too. Only their bones remain to tell of glories past.

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Fuller’s discovery was the first of a series as the South Island hinterland became known and the land was given over to agricul­ture and explored for gold. On the barren hillsides south-east of pres­ent-day Ranfurly, the Hamilton gold diggings were in full swing in 1870.

An American prospector, B.S. Booth, who had a claim at Hyde, on the other side of the Rock and Pillar Range, heard that a miner had found some moa bones when cutting peat. He went to investigate, sank a pit four feet square, and removed about 100 moa bones. Because the pit was on the “Cornishmen’s claim” he said nothing, hoping that they might move their claim pegs. He did not record what the Cornishmen thought of a stranger digging holes in their claim. Perhaps he worked quietly by night, or when the owners were elsewhere.

Booth kept an eye on the site, and when the Cornishmen pegged a new claim in December 1873 they left the pit outside. Booth excavated the site in 1874 and found several eagle bones among the remains of moa and ex­tinct geese. Had the pit been outside the claim in 1870, Booth would have pre-empted Fuller.

On another dry Otago mountain­side in the early 1870s, W.A. Low found the complete pelvis of a near-adult eagle under an overhanging rock. It was in the surface soil, and this ledge may have held the remains of an old eyrie. The exact location was not recorded, but it was some­where on the Obelisk, overlooking Alexandra.

The pelvis was sent to the Colo­nial Museum in Wellington, where Haast noticed it. It was soon taken to London, however, where it remains in the British Museum of Natural History. It is a remarkable specimen in that it still has the big ligaments which held the leg bones in their sockets. When it was found, the bone surface was still covered with mem­brane, but this does not necessarily mean that the bird had died recently. In the dry air of the Otago mountains, flesh and skin survive for thousands of years.

Deep in caves and fissures, bones were also well-preserved, but it took more effort to wrest the trophies from the earth. By far the most exciting cave find in the 19th century was at Castle Rocks. Near Lumsden in west­ern Southland, an outcrop of lime­stone has weathered into great ram­parts, fissures, and boulders. Even today, although the forest which once clothed the slopes and valley floor has long since vanished and the limestone is quarried, the Castle Rocks are impressive. The road west of the Oreti River takes you through smoothly rolling hills until suddenly, rounding a bend, you are confronted by a huge crumbling castle whose keeps and dungeons trapped and imprisoned birds over thousands of years.

Augustus Hamilton went there twice in the 1890s to search for the remains of lost birds. After his long journey by train and dray in 1893, he and his friends left the heavy work of excavation deep in the fissure to “the workers”, staying on the surface numbering and marking the bones as they were passed up. When, how­ever, “word was passed out that eagle-bones were being found”, Hamilton went down himself and excavated most of the skeleton of a male eagle, removing the dirt with a pocket-knife by the light of extra candles.

The skull was nearly perfect, and within its vault were the pupal cases of blow-fly larvae which had con­sumed the flesh hundreds of years before. Hamilton uncovered a few more bones of the larger eagle found on his first trip, then the workers exposed the entrance to a small chamber. At the very end, set in the dripstone, was the intact breastbone of the larger bird shining in the can­dlelight. The workers cut away part of the fissure wall with an axe to retrieve this prize, which now rests in the National Museum.

The Castle Rock fissure was a natural pit trap. Into it over the years fell flightless birds such as kakapo, weka, coots, kiwi and moa. But it was not so deep that all birds were killed instantly, and many survived for some time, wandering around on the bones of their predecessors until they too died of thirst or starvation. At some time, a pair of eagles was apparently attracted to the fissure by the sound of a trapped moa. Lured in by the prospect of an easy meal, they could not fly up steeply enough to escape, and died there.

Some eagles were trapped in fissures or potholes, but others died while attacking moa bogged in swamps. At the well known site of Pyramid Valley, inland from Glen-mark, Dr Roger Duff, Jim Eyles, and Ron Scarlett excavated many moa and other birds, and a few eagle bones, including two beautiful skulls. Duff’s Pyramid Valley was the main popular source of information on New Zealand’s fossil birds for many years. His picture of the South Island as a tussock-covered land filled with flocks of moa, with Haast’s eagle as a sort of megaharrier was very influen­tial.

Actually, the truth had been star­ing everyone in the face since 1873. With the moa and eagle bones in the swamps were the remains of forest trees. We now know that grasslands covered only a very small part of pre-Polynesian New Zealand, and that most species of moa were shrubland or forest dwellers.

Haast’s eagle would undoubtedly have eaten any carrion it could find, but its prey was too sparsely distrib­uted and carcases too hard to find in the forest for it to have been a regular scavenger. Such behaviour is also inconsistent with its flight pattern. It could not soar like a vulture, and could not spend long periods taking energy from the wind and thermals in its search for prey. It had to flap, and probably waited patiently for hours on high branches for prey to appear. When it did fly, it would have swept through the forests at 60­80 kilometres per hour, like the South American Harpy. High speed was essential for the wings to support the bird’s great weight.

Our new perspective on the pre human New Zealand environment owes much to the discovery of cave sites in the last 40 years. One of these is the incredible maze of passages cut through the limestone at Honey­comb Hill, near Karamea.

The National Museum, aided at first by the Forest Service and later by the Department of Conservation, has conducted detailed and pains­taking excavations in the caves dur­ing the 1980s. From moa to tiny wrens, rich faunas dating back tens of thousands of years have been care­fully brought to the light of day. Among these treasures is the largest series of eagle bones ever collected. Well over 200 bones, from more than 10 individuals which lived and died in the valley between 10,000 and 20,000 years ago, have been recov­ered, cleaned, and catalogued in the museum. Many are in perfect condi­tion, and the collection even includes the delicate tongue bones.

The large samples of individual wing and leg bones now available allow more detailed analyses of the eagle’s structure and habits than ever before. For example, we now know that the eagles which hunted moa and geese in the cool shrubland and forest of Ice Age Karamea had longer wings than those which lived around Pyramid Valley in 2500 BC, but they weighed about the same.

From the dated deposits we know, too, that as the climate grew warmer about 11,000 years ago, wet, dense West Coast rain forest replaced the drier, more open forest and shrubland in the Karamea valleys. At the same time the bird fauna changed. Some moa species moved away, and new species moved in. The eagles left the valleys, never to return. in the drier east, however, they continued to thrive until Polynesian fires and hunting exterminated the prey and destroyed the forests on which they depended.

Haast’s eagle may have survived just long enough to leave a lasting shadow across the collective mem­ory of the Maori, a dark shape plum­meting through the trees of the lost forests.